1. Field of the Invention
The present invention relates to a presence-based telephony system. More specifically, the present invention relates to a presence-based telephony system for using a Voice over Internet Protocol (VoIP) terminal to receive a call generated to a wired/wireless telephone number, and a call routing method thereof.
2. Description of the Related Art
As the Internet has been popularized, usage of VoIPs has also increased. The VoIP allows calls to the existing wired or wireless networks through a dedicated program installed in a computer, but the VoIP cannot receive calls because it has no telephone number.
To solve the problem, studies for assigning telephone numbers to the VoIPs according to a VoIP number system have been progressed.
The Internet messenger which is very popular among Internet users represents a system which uses the 3GPP Instant Messaging & Presence protocol (IMPP) to instantly transmit and receive text between computers on the Internet. The system manages presence which indicates a user's current status including the user's online access information, offline information, seat occupation information, and busy information. The above-noted presence is displayed to a buddy list of a person who has registered the user as a buddy to thereby notify the person of a time when to send a message to the user. However, the IMPP of the Internet messenger system only provides the message exchange service between computers and provides no further various services such as a call service to the VoIP or the wired/wireless networks.
As to prior art, Korean published application No. 2003-90421 entitled “Unified presence service system and method” by KT discloses a scheme for managing presence of accesses to various communication service providers by a same subscriber in a unified manner, but it fails to disclose usage of presence for call routing.
As to another prior art, Korean published application No. 2003-58557 entitled “Presence service providing method using SIP in mobile communication packet network” by SKTelecom discloses a method for using a Session Initiation protocol (SIP) to provide a presence service in the mobile communication packet network, but it also fails to disclose usage of presence for call routing.
As to another prior art, Korean published application No. 2003-68105 entitled “Device and method for providing Internet call reception switching service in mobile communication system” by Jae-ryang Ko discloses a system in which a mobile subscriber switches a call generated to the subscriber's phone number not to a mobile device but to a soft phone or an IP phone on the Internet and then answers the call, which however fails to disclose usage of presence for call routing.
As to another prior art, Korean published application No. 2003-58557 entitled “Presence service providing method using SIP in mobile communication packet network” by SKTelecom discloses a method for using a Session Initiation protocol (SIP) to provide a presence service in the mobile communication packet network, but it also fails to disclose usage of presence for call routing.
As to another prior art, Korean published application No. 2003-68105 entitled “Device and method for providing Internet call reception switching service in mobile communication system” by Jae-ryang Ko discloses a system in which a mobile subscriber switches a call generated to the subscriber's phone number not to a mobile device but to a soft phone or an IP phone on the Internet and then answers the call, which however fails to disclose usage of presence for call routing.